Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[vhooker]

I have two BT phone lines running in to my house. One line is used for business purposes and also has my broadband service operating on it, the other is a line dedicated for other purposes, this line does not have a broadband service operating on it. I have a need to re-route some of the phone wiring in the house, and one of the points to which the two lines need to be run currently has a 6 core (phone) cable run to it - but is not in use yet. I believe that only three cores are really needed to operate a phone so I would like to ascertain if I could utilise this six core cable to run both lines through using three cores for one line and three cores for the other, terminating each trio of cores on seperate BT sockets. Because of building work that has been carried out I can not really run an additional cable to intended location. I have seen a lot of discussions on various forums about interference induced by bell wires etc and so would like to understand if supporting the two phone lines over a single physical cable is likely to cause me problems. The cable run would be about 10m from the master socket. Although I am in a rural location and live quite away from the exchange my broadband service has been pretty could and the sync speed is normally about 7Mb. It would be a bit of a pain to just give it a go to see what happens (and find it does indeed have an adverse effect) so I would like to ask if there is anyone there that could offer some insight if this would be a workable proposition that would not degrade my broadband service by very much. Thanks in advance for any help and advise.

[Ottersnose]

Basically there is no issue with running 2 lines over standard  (3 pair or 6 core) Standard Twisted Pair. My only concern is that you mention running them over an extension cable which will be braided and untwisted. Could you clarify?

Cheers
Rich

[HPsauce]

I believe that only three cores are really needed to operate a phone

No, only 2. (2 and 5 in a standard socket)
Make sure each line is using a twisted pair - e.g. white/orange with orange/white.

The 3rd wire you are thinking of (3) is the "bell wire" and is redundant for modern phones. The signal on it is created by the master socket but can be omitted. If you do have an older phone that requires it then a plug-in ADSL filter local to the handset will recreate it anyway.

[Ottersnose]

I believe that only three cores are really needed to operate a phone

No, only 2. (2 and 5 in a standard socket)
Make sure each line is using a twisted pair - e.g. white/orange with orange/white.

The 3rd wire you are thinking of (3) is the "bell wire" and is redundant for modern phones. The signal on it is created by the master socket but can be omitted. If you do have an older phone that requires it then a plug-in ADSL filter local to the handset will recreate it anyway.

It would depend upon whether its being run to a master or secondary socket i.e. a socket with a bell capacitor or not.

Normal convention is:
pair 1 = white/blue blue/white
pair 2 = white/orange orange/white
pair 3 is white/green green/white

But I'm just splitting hairs

[waltergmw]

Hi VHooker,

To avoid any possible difficulties with the broadband signal I would try to install its master socket as close as possible to the building entry point with the broadband modem connected via a dual socket filter faceplate (SSFP in BT Speak) and then run any extensions you wish down your 3 pair cable.

Kind regards,
Walter

[HPsauce]

It would depend upon whether its being run to a master or secondary socket i.e. a socket with a bell capacitor or not.

Not really.
It has been commonplace advice in broadband circles for some years now to totally disconnect the bell wire throughout your wiring.

As noted above it is not normally required and can be recreated/simulated if it really is required for an "older" phone.

[AdrianH]

http://www.kitz.co.uk/adsl/socket.htm

[Ottersnose]

This is all assuming that the terminating socket has a capacitor surely? If its a secondary I.E. a 2/3a or 3/3a or 4/3a and the handset is a POT then how will it ring or have we been supplying "dodgy" analogue handsets for the last 20 years?!! (Quite possible)

[HPsauce]

Read my posts. 

[vhooker]

Thanks to every one for your help. I have to say I was really surprised how quickly people responded, so thanks everyone. I am going to try and setup the new wiring and sockets next week and see how it goes. I was just really hesitant about doing it as moving the line with the broadband on it is going to be a pain and I use that line almost all day for business. If it went wrong it would have been a major inconvenience for me. The responses have been very useful and have given me the confidence to go ahead with the planned move now. Thanks everyone.

[HPsauce]

Good luck, let us know how it goes.

And remember to keep the main signals for each line on it's own (colour-matched) dedicated twisted pair.
If you do decide (I wouldn't though) to connect up the bell wire(s) then use the 2 wires in the 3rd pair for that - mostly they'll be inactive anyway and shouldn't interfere with each other.
(though they will BOTH interfere with the broadband AT ALL TIMES by acting as radio aerials  )

[Black Sheep]

I have two BT phone lines running in to my house. One line is used for business purposes and also has my broadband service operating on it, the other is a line dedicated for other purposes, this line does not have a broadband service operating on it. I have a need to re-route some of the phone wiring in the house, and one of the points to which the two lines need to be run currently has a 6 core (phone) cable run to it - but is not in use yet. I believe that only three cores are really needed to operate a phone so I would like to ascertain if I could utilise this six core cable to run both lines through using three cores for one line and three cores for the other, terminating each trio of cores on seperate BT sockets. Because of building work that has been carried out I can not really run an additional cable to intended location. I have seen a lot of discussions on various forums about interference induced by bell wires etc and so would like to understand if supporting the two phone lines over a single physical cable is likely to cause me problems. The cable run would be about 10m from the master socket. Although I am in a rural location and live quite away from the exchange my broadband service has been pretty could and the sync speed is normally about 7Mb. It would be a bit of a pain to just give it a go to see what happens (and find it does indeed have an adverse effect) so I would like to ask if there is anyone there that could offer some insight if this would be a workable proposition that would not degrade my broadband service by very much. Thanks in advance for any help and advise.

If we think about it logically, your two circuits travel down the same cable for miles from the Exchange, along with hundreds of other circuits. It wouldn't matter a jot for another 10m of extention cable.

I think Ottersnose has got the wrong end of the stick. If ,as you quote, the extention cable is 6-core, then it won't be braided and untwisted. It will be solid-core and fully twisted. As mooted, leave the bell-wire off, if the phone is quite old just plug an ADSL micro-filter in the socket. They have their own 'ringing capacitor' installed inside them.

[sevenlayermuddle]

On a slightly pedantic note, the bellwire's purpose is not just to provide a 'ring' signal for old POTS phones, it also served the very important role of stopping these old POTS phones from interfering with one another when there were multiple extensions on a single line.

Without the bellwire, pulse dialling can be mistaken by the phones for a ring signal, and indeed it was a common fault in days of old when people hooked up (illegal) diy extensions, wrongly connected or using imported phones, when somebody dialled a number on one phone, the other phones would go 'ting-a-ling' in time with the dialling.  The ring signal generated by the microfilter does not address that aspect of the issue.

I'm not suggesting that is likely to be a problem (does pulse dialling even still work?), and  I encourage bell wire removal, but I thought it may help if anybody is curious as to why old-fashioned phones didn't just generate their own signal in the first place.

- 7LM

[HPsauce]

On a slightly pedantic note

Not at all pedantic, but totally accurate. BUT ( see below)
Somewhere in my "archives" I have the instructions on how to rewire the internals of a 1950's/60's phone to work correctly with the "new system".
The significant difference was that the "signalling mediation" for want of a better phrase was changed from being a shared responsibility between multiple phones on the line to the "new" master socket (which didn't exist before) 
This then evolved in due course to the NTE5A etc etc.....

Most actual problems came from mixing equipment from pre- and post- master socket standards, not the bell wire as such (though this did give either non-ringing or ringing-while-dialling symptoms)

[burakkucat]

(does pulse dialling even still work?)

AC9 signalling (a.k.a. loop-disconnect dialling, a.k.a. pulse-dialling) does, indeed, still work. I have a 300-series telephone, which is not quite as old as me, connected to my line. I tend to use it for receiving calls only, when I am sitting in the armchair with that telephone next to it.